The new Google Buzz highlights and worsens a significant usability challenge in the social networking space. On one hand, it makes sense for Google to add social networking functionality to its suite. If users have a need to these tools and capabilities, it makes their product more usable to integrate them into popular programs like Gmail. It also made sense for Facebook to integrate twitter-like microblogging functionality. LinkedIn and Twitter are doing this too. All of these additions makes each of these systems more powerful and more able to satisfy the diverse needs of diverse users. In theory, you can get all the social networking you need in just one system.
The problem arises because social networking requires you to use the same systems as your friends/colleagues/coworkers/etc. So if some of your friends are on Facebook, Myspace, Twitter, LinkedIn, etc, then in order to socially network with them, you also need to be on all of these and check them all and use them all. For example, to make sure my friends can read this blog, I announce new posts on Facebook, LinkedIn (when relevant) and Twitter. And sometimes I post the blog on Facebook in the first place, and then would have to announce it and link to it here.
In the end, every time an individual system enhances its usability, it makes the entire industry less usable because of all the cross posting and cross linking. If a third party creates a way to consolidate all of this in one place, then I need to learn and use another one!! Uggh.